Device for preventing sewer backflow



FIG. 1 is a perspective front, top and right side view of a device for preventing sewer backflow;

FIG. 2 is a perspective front, bottom and right side view of the device for preventing sewer backflow of FIG. 1;

FIG. 3 is a top plan view of the device for preventing sewer backflow of FIG. 1;

FIG. 4 is a bottom plan view of the device for preventing sewer backflow of FIG. 1;

FIG. 5 is a right side elevational view of the device for preventing sewer backflow of FIG. 1;

FIG. 6 is a front elevational view of the device for preventing sewer backflow of FIG. 1;

FIG. 7 is a left side elevational view of the device for preventing sewer backflow of FIG. 1; and,

FIG. 8 is a rear elevational view of the device for preventing sewer backflow of FIG. 1.

The broken lines shown in the drawings are for the purpose of illustrating portions of the device for preventing sewer backflow and form no part of the claimed design. 

CLAIM I claim the ornamental design for a device for preventing sewer backflow, as shown and described. 